Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
| Autor: | Cernicharo, José, Fuentetaja, Raúl, Agúndez, Marcelino, Kaiser, Ralf I., Cabezas, Carlos, Marcelino, Nuria, Tercero, Belén, Pardo, Juan R., de Vicente, Pablo |
|---|---|
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | A&A 663, L9 (2022) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202244399 |
| Popis: | We report the detection of fulvenallene ($c$-C$_5$H$_4$CCH$_2$) in the direction of TMC-1 with the QUIJOTE line survey. Thirty rotational transitions with $K_a$=0,1,2,3 and $J$=9-15 were detected. The best rotational temperature fitting of the data is 9\,K and a derived column density is (2.7$\pm$0.3)$\times$10$^{12}$ cm$^{-2}$, which is only a factor of 4.4 below that of its potential precursor cyclopentadiene ($c$-C$_5$H$_6$), and 1.4--1.9 times higher than that of the ethynyl derivatives of cyclopentadiene. We searched for fulvene ($c$-C$_5$H$_4$CH$_2$), a CH$_2$ derivative of cyclopentadiene, for which we derive a 3$\sigma$ upper limit to its column density of (3.5$\pm$0.5)$\times$10$^{12}$ cm$^{-2}$. Upper limits were also obtained for toluene (C$_6$H$_5$CH$_3$) and styrene (C$_6$H$_5$C$_2$H$_3$), the methyl and vinyl derivatives of benzene. Fulvenallene and ethynyl cyclopentadiene are likely formed in the reaction between cyclopentadiene ($c$-C$_5$H$_6$) and the ehtynyl radical (CCH). However, the bottom-up gas-phase synthesis of cycles in TMC-1 underestimates the abundance of cyclopentadiene by two orders of magnitude, which strengthens the need to study all possible chemical pathways to cyclisation in cold dark cloud environments, such as TMC-1. However, the inclusion of the reaction between C$_3$H$_3^+$ and C$_2$H$_4$ produces a good agreement between model and observed abundances. Comment: Accepted for publication in Astronomy and Astrophysics Letters |
| Databáze: | arXiv |
| Externí odkaz: |
|